Microwave asphalt surface treatment system

ABSTRACT

A microwave system for the treatment of asphalt surfaces that prevents the leakage of microwave radiation during use. The highly portable microwave treatment system prevents leakage of microwave radiation via a microwave horn and sealing shroud configuration that seals the unit to the asphalt surface being treated.

RELATED APPLICATION

This application is a continuation of application Ser. No. 12/817,852filed Jun. 17, 2010, which claims the benefit of U.S. ProvisionalApplication No. 61/218,152, filed Jun. 18, 2009, and U.S. ProvisionalApplication No. 61/262,378, filed Nov. 18, 2009, each of which is herebyfully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the use of microwaves for heating andtreating ground and road surfaces. Other applications include pestcontrol or extermination as well as water, waterwater, and wastetreatment via microwave radiation. More particularly, the presentinvention is directed to a microwave generator in combination with awaveguide, sealing shroud, and control system.

BACKGROUND OF THE DISCLOSURE

There has been and continues to be a very significant need for effectivemeans of thawing frozen ground. Conventional methods used today are slowand antiquated. For example some may use gas or electric energy todirectly heat the ground or use gas or electric energy to heat steam orother mediums, which in turn are applied to the frozen ground. Someprocesses call for drilling holes deep into the frost and injectingsteam or gas flames or even inserting small microwave generators in thedrilled holes. The most basic systems utilize heated water or otherliquids circulated through grids or hoses on the ground surface to thawthe ground. U.S. Pat. No. 5,838,880 to Brooks, et al., incorporated byreference herein in its entirety, describes such a system. Theseprocesses are very slow and use an extreme amount of energy.

Previous microwave ground thawing systems were either low frequency 2.45MHz or very large 915 MHz units with probes placed in predrilled holesto minimize radiation leakage. Predrilling holes for ground thawing tookas much or more time and energy then thawing with gas, steam, or othermeans. An example of a prior microwave ground thawing system isdescribed in U.S. Pat. No. 4,571,473 to Wyslouzil et al., incorporatedby reference herein in its entirety.

There continues to be the need for a more efficient ground thawingsystem that will quickly heat the ground, but addresses the health risksincumbent with microwave radiation.

U.S. Pat. No. 5,092,706 to Bowen, et al, also incorporated by referenceherein in its entirety, discloses a microwave system for repairing voidsin asphalt pavement, but utilizes a more mobile system for introducingmicrowave energy to the ground surface. This system suffers from a lackof control in directing the microwave radiation to the ground. This notonly results in inefficiency and increased operating costs, but is alsounsafe for workers in the area when the system is operational.

Another system that uses microwaves for road repair is disclosed by U.S.patent application ser. No. 11/306,979 filed by Hall and incorporated byreference herein in its entirety. This system suffers from the fact thatit is a large system and fails to address control of the microwaveradiation it generates.

Other methods and systems utilizing microwave technology for asphaltroad repair include U.S. Pat. Nos. 4,252,459, 4,252,487, and 4,319,856to Jeppson and 4,347,016 to Sindelar et al., all of which areincorporated by reference herein in their entirety.

SUMMARY OF THE INVENTION

A microwave generation unit of the present invention addresses thedeficiencies of prior art ground thawing systems by eliminating the needto prepare the ground by drilling holes for placement of probes thatconduct the microwave radiation into the ground. Instead, the microwavegeneration unit of the present invention comprises a waveguide andsealing shroud that directs microwave energy into the ground from thesurface, thus eliminating time-intensive ground preparation. The sealingshroud ensures that microwave radiation leakage is minimized and keptwithin occupational safety standards.

The present invention provides a system that utilizes microwaves topenetrate into the frozen ground to provide heating and thawing. Themicrowaves are controlled and monitored using microprocessors and aunique feedback system. Microwave leakage is eliminated by using aliquid filled bladder between the frozen ground and the microwavegenerator. Microwaves are generated at 915 MHz ranging from 1 to 100 kwand directed through a special waveguide into the frozen ground. Sensorsin and around the wave guide monitor the microwave power level,microwave bounce back, ground temperature, and any radiation leakage andthe information is fed to a microprocessor.

The invention consists of 915 MHz generator, wave bounce back waterload, a wave guide, a wave guide horn, wave guide venting blower, groundsealing bladder, wave leak detectors, wave bounce back sensors,temperature sensors, and microprocessor controller. The complete unit isvery portable and can be moved quickly from area to area as it generallytakes less than 30 minutes to thaw a nine square foot area.

In another aspect of the present invention, a microwave generation,delivery, and control system is utilized for asphalt road repair. Thesystem described above is used for heating and treating asphalt roadsurfaces to repair voids (i.e., potholes). The ability to isolate andcontain heating of asphalt allows for precision in making repairs. Theability to quickly heat a specific surface also allows for year-roundroad repair, even in the coldest climates.

In yet another aspect of the present invention, the microwavegeneration, delivery and control system is utilized for pest control ofinsects (e.g., red ants) or rodents (e.g., gophers) by safely directingradiation at known areas of infestation to kill the pests. A furtheraspect of the present invention includes the use of microwave energy tosterilize water, wastewater, and waste materials.

The above summary of the various aspects of the disclosure is notintended to describe each illustrated embodiment or every implementationof the invention. The figures in the detailed description that followmore particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE FIGURES

The embodiments of the present invention may be more completelyunderstood in consideration of the following detailed description ofvarious embodiments in connection with the accompanying drawings, inwhich: FIG. 1 is a rear perspective of an embodiment of the presentinvention.

FIG. 2 is a side perspective of an embodiment of the present invention.

FIG. 3 is a side elevation of a curved portion for the waveguide of thepresent invention.

FIG. 4 is a front elevation of a rotary joint for the waveguide of thepresent invention.

FIG. 5 is a close-up view of the sealing shroud of the presentinvention.

FIG. 6 is a plan view of the sealing shroud of the present invention.

FIG. 7 is a cross-sectional view of the bladder portion of the sealingshroud of FIG. 6.

FIG. 8 is a schematic of the cooling system of the present invention.

FIG. 9 is a perspective of an alternative embodiment of the presentinvention.

FIG. 10 is a side elevation of a third alternative embodiment of thepresent invention.

While the present invention is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the presentinvention to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the present invention.

DETAILED DESCRIPTION OF THE FIGURES

Referring now to FIGS. 1-7, a microwave ground heating system 100 of thepresent invention comprises a microwave generator 102, waveguide 104,horn 106, sealing shroud 108, and control system 110. The microwavegenerator 102 includes a magnetron 112 capable of producing microwavespreferably at 915 MHz ranging from 1-100 kw. This embodiment allows formounting on a vehicle 114 for system mobility. The microwave generator102 will typically require a 3-phase, 460 volt ac power supply 116 thatcan be mounted on the vehicle 114 or provided from an outside source.

Due to the large quantities of microwave energy used in the presentinvention, a waveguide 104 will be required to direct the microwaveradiation from the microwave generator 102 to the horn 106 forapplication to the ground or road surface 118. The waveguide 104consists of non-ferris metals of a thickness of at least ¼ inch. Thewaveguide 104 of the present invention is preferably comprised ofrectangular channels 120, 122 of varying lengths and configurations,such as the curved channel 123 of FIG. 3. The waveguide 104 is notlimited to rectangular shape and the present invention contemplates anyshape known in the art of microwave energy guidance. To permitarticulation of the waveguide 104, one or more rotary joints 124 may beused between channels 120, 122, 123. Rotary joints for waveguides arewell known in the art. Examples include U.S. Patent No. 2,830,276 toZaleski, U.S. Patent No. 4,757,281 to Anne et al., and U.S. Pat. No.3,011,137 to Albanese, all of which are incorporated herein by referencein their entirety. Connections between rectangular channels 120, 122,123 as well as with rotary joints 124, are preferably made with bolts126 to allow for relatively easy assembly and disassembly of thewaveguide 104. However, it is contemplated that the connections betweenthe various parts of the waveguide 104 can be accomplished by othermeans such as welding or clamping. For additional stiffness and toprovide attachment points for support of the waveguide 104, steel orother stronger metals may be used on the exterior of the waveguide. Oneembodiment can be a frame 128 as illustrated in FIG. 1. A wave guideventing blower 130 may be used to eliminate any heat or moisture buildupin the waveguide 104.

In the presently disclosed embodiment, the waveguide 104 may be movedand placed in a fashion similar to that of a backhoe. For larger orlonger waveguides 104, hydraulic systems can be used to move the variousparts as with a backhoe boom. Further, the rotary joints 124 of thewaveguide 104, as depicted in FIG. 4, will allow the horn 106 to betilted for non-horizontal application of microwave energy such as tosloped ground.

In the presently contemplated embodiment, the waveguide 104 directsmicrowave energy through the horn 106 for application to the ground orroad surface 118. The horn includes several ventilation ports 132 toallow steam produced during the heating of the ground or road surface118 to dissipate. To provide a close-fit of the horn 106 to the groundor road surface 118 and limit microwave radiation leakage, a sealingshroud 108 is fitted to the bottom edge of the horn 106 as shown in FIG.5. The sealing shroud 108 is comprised of a canvas cover 200 fordurability and an inflatable rubber bladder 202. For a horn 106 with afootprint of approximately 30 inches by 30 inches, the canvas cover 200is preferably ⅜ inch in thickness and the rubber bladder 202 ispreferably ⅛″ in thickness. The horn can be sized for variousapplications, from a post hole sized horn to a 6-foot by 4-foot sizedhorn for trenches. The sealing shroud 108 will vary in size andconstruction accordingly. The sealing shroud 108 also includes inlet andoutlet ports 204, 206 for circulation of coolant 208. Coolant 208 ispreferably a 50-50 mixture of water and glycol, but can be any form ofcoolant known to those skilled in the art of liquid cooling.

The horn 106 includes several RF sensors 210 located preferably in closeproximity to the sealing shroud 108 and spaced around the horn 106 tomonitor leakage of microwave radiation.

A liquid cooling system 300 as illustrated in FIG. 8 is provided to coolthe sealing shroud 108 during operation of the microwave ground heatingsystem 100. The liquid cooling system 300 comprises an inlet pump 302,an outlet pump 304, a coolant storage tank 306, a temperature monitor308, and a pressure regulator 310 to circulate the coolant through thesealing shroud 108. Preferably, the inlet and outlet pumps 302, 304 runon 110 volt ac and capable of pumping 30 gallons per minute at 30 psi.In the preferred embodiment of microwave ground heating system 100 witha horn 106 that is 30 inches by 30 inches in footprint, a 1/2 inchcoolant line 316 circulates coolant 208 at a rate of 3-7 gallons perminute at a pressure of 1-3 psi. The system is controlled by a pressureregulator 308, temperature monitor 310, and valves 312, 314 by thecontrol system 110. For this configuration, the coolant storage tank 306should have a volume of at least 15 gallons.

The present invention also includes a control system 110 with amicroprocessor 400 to monitor and control the operation of the microwavegenerator 102. The control system 110 is programmed to allow inputs suchas type of surface to be heated (e.g., clay, sand, asphalt), types ofburied utilities, and time to thaw, which will then allow control system110 to regulate and monitor the operation of the microwave generationunit 102. The control system 110 includes temperature sensors (notshown) and microwave bounce back sensors (not shown) to collect data forcontrol and operation of the microwave generator 102. The control system110 also receives feedback from the several RF sensors 210 to moderatethe microwave energy produced and, if necessary, completely shut downthe microwave generation unit 102. The control system 110 also managesthe liquid cooling system 300.

In operation, the horn 106 with attached sealing shroud 108 is placed onthe ground or road surface 118 to be heated or thawed. Sealing shroud108 placement is confirmed to ensure that there are no large gapsbetween it and the ground or road surface 118 that could result inmicrowave leakage. The control system 110 is then energized and runs aself check to ensure that it has proper communication with otherelements of the microwave ground heating system 100. The liquid coolingsystem 300 is then energized via the control system 110 to circulatecoolant 208 prior to energizing the microwave generator 102. As theliquid cooling system 300 pumps coolant 208 into the rubber bladder 202,the sealing shroud 108 expands to fill any gaps between the horn 106 andground or road surface 118.

The control system 110 then performs a check of all functions of themicrowave generation unit 102. This entails warming up the microwavegeneration unit 102 and supplying it with low power, approximately 3.0kW, to check parameters such as microwave leakage at key junctions:microwave generation unit 102 to waveguide 104; between rectangularchannels 120, 122, 123; between rectangular channels 120, 122, 123 androtary joints 124; between rectangular channels 120, 122, 123 and thehorn 106; and between the horn 106 and the ground or road surface 118.If any parameter exceeds specifications, the control system 110 shutsdown the microwave generation unit 102 and the control system 110indicates via visual and or audio signals where the microwave groundheating system 100 exceeds specifications. Corrections can be made bythe system operator and the procedure can be started from the beginning

Another embodiment of the microwave ground heating system 100 isillustrated in FIG. 9. In the alternative embodiment shown in FIG. 9,all of the elements of the microwave ground heating system 100 exceptfor the power supply are provided in a stand-alone unit 500. Thestand-alone unit 500 comprises the control system 110, microwavegeneration unit 102, liquid cooling system 300, horn 106, and sealingshroud 108 of the previously disclosed embodiment. The stand-alone unit500 eliminates the need for the waveguide 104 of the previouslydisclosed embodiment. The power supply 116 of the embodiment shown inFIG. 10 can be truck mounted with a boom to assist in placement of thestand-alone unit 500.

A third embodiment of the microwave ground heating system 100 isillustrated in FIG. 10. In the alternative embodiment shown in FIG. 10,the elements of the microwave ground heating system 100 are provided ina split configuration with some of the elements provided on a base unit600 and others elements provided on a transport vehicle 610. The baseunit 600 comprises at least the horn 106 and sealing shroud 108 of thefirst disclosed embodiment. The power supply is provided on thetransport vehicle 610. The control system 110, microwave generation unit102, and liquid cooling system 300 of the first disclosed embodiment canbe constructed with the base unit 600 or provided on the transportvehicle 610.

Other Applications

Another application contemplated by the present invention is the use ofthe microwave ground heating system 100 for road repair. The ability torepair roads, especially asphalt roads, during late fall through winterand early spring is limited in many parts of the world due to coldtemperatures. The compacted base cools the asphalt too quickly before itis packed to the optimal air content. Therefore, repair of roads duringthis time frame is usually limited to repairs with cold-mix asphalt.Such repairs are temporary and will usually require replacement with ahot-mix asphalt when temperatures moderate. Thus, there is a need toprovide a portable heating system that can quickly and efficiently heatthe area of an asphalt void (i.e., pothole) during cold temperaturesthat will allow hot-mix asphalt repair.

U.S. Pat. No. 5,092,706 to Bowen, et al, incorporated by referenceherein in its entirety, discloses a microwave system for repairing voidsin asphalt pavement, but utilizes a more mobile system for introducingmicrowave energy to the ground surface. This system suffers from a lackof control in directing the microwave radiation to the ground. This notonly results in inefficiency and increased operating costs, but is alsounsafe for workers in the area when the system is operational.

Another system that uses microwaves for road repair is disclosed by U.S.patent application Ser. No. 11/306,979 filed by Hall and incorporated byreference herein in its entirety. This system suffers from the fact thatit is a large system and fails to address control of the microwaveradiation it generates. Other methods and systems utilizing microwavetechnology for asphalt road repair include U.S. Pat. Nos. 4,252,459,4,252,487, and 4,319,856 to Jeppson and 4,347,016 to Sindelar et al.,all of which are incorporated by reference herein in their entirety.

Yet another application contemplated by the present invention is the useof the microwave ground heating system 100 for pest control. Insect androdent infestations can be problematic to rectify because these pestsare typically found below the ground surface. Typical treatment for redants or gophers is to soak a known area of infestation with poison. Thisremedy has the shortcomings of potential health risks, especially foryoung children, and environmental damage. The current invention killsthe insects or rodents below grade while leaving no waste productsbehind.

Other applications of the invention disclosed herein include utilizationof microwaves as a disinfectant in the treatment of water andwastewater. In the same vein, it is contemplated that the inventionherein described may be used in the treatment of waste materials todisinfect and decontaminate the waste prior to disposal or otherdispensation. The material to be treated would be conveyed under thehorn of the microwave ground heating system 100 via any of the meansknown in the art.

It will thus be seen according to the present invention a single use,disposable filtration system for pharmaceutical application andassociated methods of use have been disclosed. While the invention hasbeen described in connection with what is presently considered to be themost practical and preferred embodiment, it will be apparent to those ofordinary skill in the art that the invention is not to be limited to thedisclosed embodiment, that many modifications and equivalentarrangements may be made thereof within the scope of the invention,which scope is to be accorded the broadest interpretation of theappended claims so as to encompass all equivalent structures andproducts.

1. A system for treating asphalt surfaces, comprising: a microwavegeneration system; a waveguide; and a microwave horn comprising anon-conductive sealing shroud.
 2. The asphalt surface treating system ofclaim 1, wherein the sealing shroud comprises an inflatable bladder. 3.The asphalt surface treating system of claim 2, wherein the sealingshroud further comprises a durable, flexible cover.
 4. The asphaltsurface treating system of claim 3, further comprising a cooling systemcirculating liquid coolant through the inflatable bladder.
 5. Theasphalt surface treating system of claim 1, wherein the waveguidecomprises multiple members that can be joined in various configurations.6. The asphalt surface treating system of claim 5, wherein the waveguidefurther comprises a rotary joint.
 7. The asphalt surface treating systemof claim 5, wherein the waveguide further comprises and externalskeleton.
 8. The asphalt surface treating system of claim 1, whereinmicrowave horn comprises an RF sensor.
 9. The asphalt surface treatingsystem of claim 8, wherein microwave horn further comprises aventilation port.
 10. The asphalt surface treating system of claim 1,further comprising a control system.
 11. The asphalt surface treatingsystem of claim 10 wherein the control system comprises a programmablemicroprocessor that monitors the generation and leakage of microwaveradiation from the heating system.
 12. The asphalt surface treatingsystem of claim 11 wherein the microwave generation system generatesmicrowaves at 915 Mhz.
 13. An asphalt surface treating system,comprising: a microwave generation system; and a microwave horncomprising a non-conductive sealing shroud, the sealing shroudcomprising inflatable bladder and a durable, flexible cover.
 14. Theasphalt surface treating system of claim 13, further comprising acooling system circulating liquid coolant through the inflatablebladder.
 15. The asphalt surface treating system of claim 14, furthercomprising a control system.
 16. The asphalt surface treating system ofclaim 15 wherein the control system comprises a programmablemicroprocessor that monitors the generation and leakage of microwaveradiation from the heating system; and the microwave generation systemgenerates microwaves at 915 Mhz.
 17. A method of treating an asphaltsurface comprising: generating microwave radiation at 915 Mhz; directingsaid microwave energy to the asphalt surface via a waveguide and horn;preventing the leakage of microwave energy between the horn and theasphalt surface by providing a non-conductive sealing shroud between thehorn and the asphalt surface.
 18. The method of claim 17, furthercomprising: providing a cooling system circulating liquid coolantthrough the sealing shroud.
 19. The method of claim 18 wherein thesealing shroud comprises an inflatable bladder and a durable, flexiblecover.
 20. The method of claim 19, further comprising: providing acontrol system with a programmable microprocessor to monitor thegeneration and leakage of microwave radiation from the treating system.